Ответ:

  1. Does Gleb visit an animal shelter every weekend?
  2. Does he help his grandparents in the garden?
  3. Do they avoid him at school?
  4. Do you like simple clothes?
  5. Does she understand the main lesson?

В вопросе Present Simple перед подлежащим ставится do или does; основной глагол употребляется в начальной форме.